EFFECTS OF PYROLYSIS TEMPERATURE AND RETENTION TIME ON THE PHYSICOCHEMICAL PROPERTIES OF CORN COB-DERIVED BIOCHAR FOR SUSTAINABLE SOIL MANAGEMENT

Abstract

Corn cobs are an abundant agricultural residue with considerable potential for conversion into
biochar as a sustainable soil amendment. This study evaluated the effects of pyrolysis temperature
and retention time on the physicochemical properties of corn cob-derived biochar to determine
the optimum production conditions for sustainable soil management. A 3 × 3 factorial experiment
arranged in a Completely Randomized Design (CRD) with three replications was conducted
using three pyrolysis temperatures (300, 400, and 500°C) and three retention times (1, 2, and 3
h). The produced biochar was characterized for biochar recovery, pH, organic matter, total
nitrogen, and macro- and micronutrient contents. Analysis of variance (ANOVA) revealed
significant effects of pyrolysis conditions on most biochar properties. The highest biochar
recovery (42.67%) was obtained at 500°C for 2 h, indicating the most efficient biomass
conversion. All biochar samples were strongly alkaline (pH 9.31–9.98), suggesting their
suitability for ameliorating acidic soils. Biochar produced at 300°C for 3 h contained the highest
organic matter (47.02%) and nitrogen (2.35%), whereas 500°C for 2 h yielded the highest
phosphorus (20.45%) and calcium (1.28%) concentrations. The greatest potassium (3.09%) and
sulfur (0.70%) contents were obtained at 500°C for 1 h, while 400°C for 1 h produced the highest
available iron (1.73%). Magnesium and manganese contents were only minimally affected by the
pyrolysis treatments. Overall, pyrolysis at 500°C for 2 h provided the best balance between
biochar recovery, carbonization efficiency, and nutrient enrichment, making it the optimum
condition for producing high-quality corn cob-derived biochar. The optimized biochar shows
considerable potential as a climate-smart soil amendment for improving soil fertility, enhancing
nutrient-use efficiency, and promoting sustainable agricultural production.